Are they Cousins?

Question

Please help with this family tree question. What relationship is my daughter to this same age girl?

My father's first cousin's great- granddaughter.

(My grandmother's sister had a son. This son had a daughter. This daughter now has a 7 year old granddaughter).

How is this 7 year old related to my daughter?

Thank you in advance...

Answer 1

Your daughter and this 7-year-old great-granddaughter of your father's first cousin are third cousins once removed.

Your grandmother and her great-great-grandmother were sisters. Your father and her great-grandfather were first cousins. You and her grandmother were second cousins. Your daughter and either her mother or father were third cousins. Your daughter and this girl, who is one generation different, are third cousins once removed.

The "removed" bit pertains when two people are of different generations. You and your father's first cousin are first cousins once removed.  Your daughter and your father's first cousin are first cousins twice removed.

Answer 2

she would be your daughter's 3rd cousin once removed.

once removed means there is a generation age gap.

for example, your first cousin would be your daughter's first cousin once removed.

Answer 3

Third cousins once removed = the two people who are related as follows: Parent's parent's parent's sibling's child's child's child's child.

A third, or fourth, (etc.) cousin, without the once, twice, (etc) removed, would simply be the same number of generations down from the siblings.

But then once removed would be when the relationship add's an extra child on one line; twice removed would be two generations extra on one line.  

It appears that the Cousin number uses the smaller number (since technically couldn't you go backwards and say fourth cousins once preremoved?), and the x-th removed adds on that many generations on one line; however I ask experts to clarify this.

--not expert, sorry

Even though  they're the same age, they're different generations apart from the siblings.  So you need once removed, since there is one more generation on one than on the other,

PS they probably would have 1/256 the same DNA, although if the siblings were identical twins it goes up, or if they are related in more than one way.  However, 1/256 DNA probably doesn't exist, and it would likely be 0 chromosomes the same, or else probably just one.