Do 3rd cousins share the same DNA?

Question

My cousins and I have the same great great grandparents, we assume that we are 3rd cousins and wonder if we have share the same DNA

Answer 1

Yes, you have common DNA but it will be hugely diluted by the ancestors you do not have in common.  You only share an 8th.

Answer 2

You are correct that you are 3rd cousins IF your g-g-grandparents are also his g-g-grandparents.  Since each person has 16 g-g-grandparents, and that you share 2 of them (because they are paried up in 8 husband-wife couples), then you share 1/8th of the same DNA.

Answer 3

Sort of. Assuming siblings share all the DNA.

1st cousins share 1/2

2nd cousins share 1/4

3rd cousins share 1/8th

and so on. Note what others have said - each person's DNA is different, so siblings will share genes pulled from the same pool, but their collection will be unique.

Answer 4

You would share DNA of your common ancestor.

Answer 5

If your cousins are male, and you are male, they will have the same Y-DNA as you, if they are female and you are male or female they will not share the same mtdna as you.

If you are female, you only carry your mother's Mtdna, and her mother's Mtdna, and her mother's Mtdna etc.,etc.,etc. and that will show only your mother's lineage (you will pass that Mtdna on to your daughters and sons, but your sons will not pass it on to their children). You do not inherit your father's Y-DNA.

If you are male, you inherit your father's Y-DNA, his father's Y-DNA, his father's Y-DNA, and so on back to your origin. You also inherit your mother's Mtdna, but you only pass your Y-DNA on to your sons.

Answer 6

You don't share the SAME DNA with anyone else in the world. It's unique to each individual; even in the cases of identical twins.

You would share some of your DNA with third cousins though, and this would be the DNA of the common ancestor you share. However, it would be diluted in you both.