First cousins
Your first cousin (sometimes called a full cousin, but usually just a cousin) is the child of your aunt or uncle. The most recent ancestor you and your first cousin share is your grandparent. You typically share 12.5 percent of your first cousin’s DNA.

Second cousins
Your second cousins are the children of your parents’ first cousins. Take a look at your family tree, and you’ll see that you and your second cousins have the same great-grandparents. You typically share 3.125 percent of your second cousin’s DNA.

Third cousins
Of course, cousinhood doesn’t end there. You have likely also heard the term third cousin and wondered what that means. For third cousins, great-great-grandparents are the most recent common ancestor, and you share .781 percent of your DNA. You get the picture.

What is a second cousin once removed?
If you’re puzzled over the expression “second cousin once removed” or “twice removed,” you’re not alone. Luckily, the answer is simple: All cousins share a common ancestor. Your “degree of cousinhood” (second, third, fourth) depends on how many generations back that common ancestor is.

How to calculate cousin removes
“Removes” enter the picture when two relatives don’t have the same number of generations between them and their most recent common ancestor. One generation difference equals one remove.

Double cousins
You may have heard people say they’re double cousins. That’s a special cousin category for the offspring of brothers- and sisters-in-law—for example, your sister weds your husband’s brother. Instead of sharing one set of grandparents, as first cousins do, double cousins share both sets of grandparents. As you might expect, double cousins have more DNA in common than typical first cousins—about 25 percent.

“Kissing” cousins
Despite how it sounds, a kissing cousin isn’t a cousin you marry. Rather, it’s any distant relative you know well enough to kiss hello at family gatherings. Now we’re begging the question: How close a cousin is too close to wed? States have different laws governing consanguineous marriages (and we’ve heard all the jokes, so just stop right now). It’s best to ask a lawyer about statutes for the state in question.