My fiance's great grandfather and my great grandfather were half brothers....how are we related if at all??

Question

We didn't find out till 4 years AFTER we started dating! Should we be worrying. I've been doing research....half siblings only carry 25% of the same genes so if you divide that out down the generations if comes out to very little. I jsut need some reassuring

Answer 1

Be reassured, your current fiancee although still related, is the equivalent to a third cousin removed, of which sits comfortably in the Legal department.

Now EXHALE,

Regards,

Bravo.

Answer 2

You are like fourth cousins that share only one great great grandparent ....Be reassured. There is no legal or genetic problems

Answer 3

You share one great-great grandparent out of sixteen.  You are half-third cousins.  It would take some spectacularly bad luck against long odds for the two of you to have any genetic problems.

I'm sure the story of how you discovered the relationship is interesting.

Answer 4

You are worrying too much..... You are only slightly related..... Most americans have ancestors that are related and dont know about it..... Its not like your going to have 3 eyed kids or something.... Not to sound weird but even with animals - a small amout of inbreeding makes the blood lines stronger..... Your boyfriend and you are mathmaticaly genetically displaced 16 times or more.... Not enough to lose sleep over... Actual way back in the 19th century and earlier it was commonplace for people to marry first cousins.  Why? The human race didnt have mass transit so this limited the amount of people in a geographic area they could marry.... Well guess what? The human race survived didnt it?... Only recently in the 20th century has it become taboo to marry a relative... Some states have laws against marrying a 1st cousin. This probably isnt a bad idea...... Second cousins, third cousins or 1/2 brothers and sisters of second cousins are fine to marry and produce healthy offspring......  Shhhh - the queen of England, Charles and all those bluebloods are all slightly related to each other by marrying close family members (1st cousins ~ not recommended) and they have done just fine......... You are geneticaly quite displaced enough from your fiance that it isnt even an issue!

Answer 5

Oh, yeah, you are definitely related (but then, we all are).  You could both have the same g-g-grandfather and still not be closely related; being that they were half brothers, the relationship (blood line) is too remote to make a difference.  I cannot say exact; why? because at each generation there is 2 ways to go...

You can read a book such as "Trace Your Roots with DNA" by Megan Smolenyak Smolenyak and Ann Turner.  On p. 120, they have a table explaining the commonality of DNA with some relatives.  You share a mere 12.5% of your g-g-grandfather's DNA; if you divide that in 2 (half brothers) you would have 6.25%, which is the most that either of you would have in common with a common ancestor; you two would be "half" second cousins, twice removed (0.781% shared DNA) [i.e., you would have "half" of that 0.781%...really negligible).  In other words, don't worry about it.  Many people marry 2nd cousins, even first cousins with no problems.

Answer 6

You are hardly related. Its an interesting story. But there is not really any genetic mutatuions through children or anything to worry about. Im sure many of us would be surprised if we traced our spouses family lineage back up the family tree. Its not uncommon to have a small trace of a certain bloodline that is inheritant of people from similar historical areas, cultures, excetera. Your Gene pool is good to go. If you love ur fiance then go for it.

Answer 7

It is easy to see if you work it out one generation at a time. Call your GGF Albert and his Andrew, their sons Bruce and Bob, and so on:

Albert & Andrew = half brothers

Bruce & Bob = Half 1st cousins

Charles & Clarence = half 2nd cousins

JKC & Fiance = half 3rd cousins

Unless hemophilia or another genetic disorder runs in your family, you'll be fine. Most of the people in the USA with ancestors who were out of the big cities before 1880 have first, second or third cousins who married each other in their family trees.

Half siblings carry 50% of the same genes, don't they? The half they get from their common parent?

Answer 8

your related somehow but its very far away. so you should be fine