Likewise, your second cousin once removed is the child of your second cousin, or the second cousin of your parent, and so on. Let's say my father, Stan, married a woman named Mary, and they had me, Robert; Stan also has a child from a previous marriage, Peg.Stan's brother Arthur married Mary's sister Delinda; they had Sam.
Tom and I are full first cousins; we share one pair of grandparents.
Sam and Peg are half first cousins; they share only one grandparent.
Sam's child Yvonnne is my first cousin once removed; we don't share any grandparents, but she is the child my first cousin (or, from her point of view, I am the first cousin of her parent).
This zombie thread on whether sex between adopted siblings is incest just popped up on my control panel, so I thought I'd start a someone-related thread.
Here's the sitch: For purposes of this discussion, assume you are unmarried and unattached.
Let's say that you meet a person with whom you share an immediate and mutual attraction.
You date long enough that both are you are willing to have sex.
But before you do so, you discuss that you're some variety of cousin. First cousins are persons whose nearest common ancestor is the grandparent of both.
How close is too close for your comfort--that is, so close that you'll have to end the romantic relationship? Full first cousins share a pair of grandparents (in other words, the linking parents of the FFCs were full sublings); half first cousins share only one grandparent (that is, the linking parents were half siblings.) Double first cousins are full first cousins who share all four grandparents.