How many years are in a generation?

Question

How many years are in a generation?

Answer 1

30 years, to be exact.

Answer 2

you cant say that it depends how old the mother was when she started the next generation

lets say she had a child at 15, her daughter had a child at 22 the daughters child had a baby at 16

so u cant say

Answer 3

1000

Answer 4

As others have said, there's only a guideline, not a rule, to the number of years in a generation.

During periods of war fewer babies are born and the gap between generations can increase. Or, if maternal mortality is high and a first wife has five children and dies, the second wife could be 10 years younger than the husband. That will distort the "generation" figure as well.

Answer 5

Webster's defines it as "the average interval between the birth of parents and the birth of their off-spring."  

Answer 6

About 15-20, but there is no precise definition.

A generation is a rough estimate of the time lapse between when one wave of children in a family is born, and when those kids grow up and have kids of their own.

Answer 7

the term of years, roughly 30 among human beings accepted as the average period between the birth of parents and the birth of their offspring.

Answer 8

25 at best guess. It varies, and has increased recently in developed countries (due to contraception). I always use 25.

Men didn't usually marry until they had done their apprenticeship (at 21), so this was a practical minimum for most. Most women had their first child at around 20.

Answer 9

The number of years in a generation will vary from generation to generation, with my own family, from my grand-children back to my 8Xgrandfather it is between 19 and 22 years per generation...with one exception of  45 years ! As a general rule one generation was normally always reckoned to be 20-25 years, but there have of late been a few population studies which claim to show that one generation, as an average guide, should probably be reckoned at 30 years. I personally would stick with the 20-25 year average, it seems to work for most people!

EDIT:

Average number of years per generation

TREMLAY, M. & VÉZINA, H. (2000).

New Estimates of Intergenerational Time Intervals for the

Calculation of Age and Origins of Mutations. American Journal of Human Genetics, 66, 651-658.

Abstracted section :

Intergenerational time intervals are frequently used in human population-genetics studies concerned with the ages and origins of mutations. In most cases, mean intervals of 20 or 25 years are used, regardless of the demographic characteristics of the population under study. Although these characteristics may vary from prehistoric to historical times, we suggest that this value is probably too low, and that the ages of some mutations may have been underestimated. Analyses were performed by using the BALSAC Population Register (Quebec, Canada), from which several intergenerational comparisons can be made. Family reconstitutions were used to measure interval lengths and variations in descending lineages. Various parameters were considered, such as spouse age at marriage, parental age, and reproduction levels. Mother-child and father-child intervals were compared. Intergenerational male and female intervals were also analyzed in 100 extended ascending genealogies. Results showed that a mean value of 30 years is a better estimate of intergenerational intervals than 20 or 25 years. As marked differences between male and female interval length were observed, specific values are proposed for mtDNA, autosomal, X-chromosomal, and Y-chromosomal loci......

Journal Title:

American Journal of Human Genetics ISSN 0002-9297 CODEN AJHGAG

Answer 10

20

Answer 11

The duration usually used in professional studies is 25 years.

Answer 12

People use certain figures for "averages" which is fine, when you are estimating.  You also have to take into account whether this is being used with a female or a male.. men "tend" to have children at older ages, for purely biological purposes, women won't have children past a certain age.

My grandfather was 70 when my mom was born.  She was the youngest of his 2nd family (he remarried after his 1st wife died to much younger woman).  His is the male end of the spectrum.  (and I was not born until my mom was 40).  I also had my children "late".

I really envy families who have those pictures of 4 (or 5!) generations in a picture.  

My daughter had her first child at 16.  She is the female end of the spectrum.  Generally, in the 1800s, you find women married young, having babies approximately every 2 yrs (no birth control), so a family of 12 or more is not rare at all.  If you are looking at census records, you almost come to expect this pattern.. if there is a gap of 4-5 yrs between babies, good chance that one has died.

Eventually, genealogists do look at average ages if trying to estimate a birth date, based on eldest known child.  On the other hand, if we succeed in finding ancestors, we have specific dates to see how long it really is/was.  

From popular terminology... baby boomers are the specific generation born following WW2.. normally, to the soldiers who came home. They made up for lost time, hence a boom in babies.  Baby boomer's children are the next generation.. don't know the popular term.

The bottom line... it is a flexible term/ definition.  

Answer 13

I think 100years.

Answer 14

A generation has traditionally been defined as “the average interval of time between the birth of parents and the birth of their offspring." This makes a generation around 30 years in length. However, while this rule of thumb has served sociologists well in analysing generations up to and including the Baby Boomers, it is less relevant for recent generations.

Firstly, because cohorts are changing so quickly in response to new technologies, changing career and study options, and because of shifting societal values, their characteristics can change in less than two decades. Secondly, the time between birth of parents and birth of offspring has stretched out from two decades to more than three. Looking at Australian statistics, the median age of a woman having her first baby was 24 in 1976, while today it is just over 30. So, while the Boomers are the children of the Builders or Veterans, Gen Z are often the younger siblings of Gen Y – or the children of the late-breeding Gen X. In recent years, the median age of first-time mothers throughout the western world has reached record highs.

    * USA - 25.2[3]

    * UK - 27.4[4]

So, today a generation refers to a cohort of people born into and shaped by a particular span of time (events, trends and developments). And the span of time has contracted significantly.

Answer 15

Here's a great write up about it

http://archiver.rootsweb.ancestry.com/th...

The reason for the disparity between the 20yr/gen and the 30-33yrs/gen is

very simple.

The 30-33yr figure is an oft quoted figure in genealogical circles and has

arisen from experience; many people researching their family history find

that, over 3 or 4 or more generations it works quite well (of course there

are occasional lines when it doesn't; that is what statistics is all about);

on average it works quite well. I read about it when I was setting out on my

researches, and was a bit 'sniffy' about it; but I must now confess that it

does seem to fit surpisingly well.

The 20yr figure is used by academic DNA reserarchers who are not confining

their interests to the recent past (hundreds of years) but right back to

pre-history (tens-of-thousands of years) over which most of the generations

will have been in more 'primative' societies where the breeding interval

probably started a little earlier and certainly ended a lot earlier than

they do in post AD1000 societies. In a primative agricultural or

hunter-gatherer society a breeding period of 15-ish-to-25-ish is quite

reasonably. To continue breeding into the mid-to-late thirties, as is common

in western society post AD1000, would be very rare in a primative

population.

This whole debate has arisen from people thinking that the academic

DNA-researchers are interested in modern genealogy; they are not: their

interest is in genealogical and demographic changes that occur over

millennia and tens of millennia. They are not greatly, or mainly,

interested in recent genealogy, and hence do not use figures applicable to

that era.

The academic DNA-researchers are not doing all this for our benefit, and it

is disappointing that so many people don't seem to realise this.

Dave Andrews

Bristol UK

Answer 16

about 100 or so

Answer 17

Generation has many meanings, with different values. None of them are exact.

Anywhere from 13 - 80, but usually 20 - 40 for "The length of time between a person's birth and his/her child's birth", (That is, how old the mother/father was at any particular child's birth.)

27 - 35 for "The average age in my family between parents and children". That is, if the parents were the same age and had children at age 24, 28, 30 and 32, the generation for them would be 29 years. If you were doing genealogy, you'd compute the averages for each family, then the average of averages. In my family, thanks to a great grand father who had his first child at age 40 and his last at age 57, the average for all 8 great grandparents is 33. Most people use 30 as a general rule, when estimating birth years. So, if someone was born in 1810, there is a good chance his grandparents were born about 1750. I don't put that down as their birth date, but I would look harder at the people in Madison County named Pack who were born in 1740 - 1760 than at those born outside that range.

The "Baby Boomers" were the children born to the soldiers who came home from WWII, got married and started procreating. That generation is about 10 years in span, 1945 - 1955. The generations that have names are about 10 years long; BB, already mentioned; the lost generation, the beat generation, X, Y and so on.