How can your cousins be your siblings/parents be your siblings or grandparents?

[Chloe]

I got this idea because I saw this person post on Facebook that their cousins were also their siblings.. It both freaked me out and confused me.. It also reminded me of the song, "I am my own grandpa".

[Grace N]

They could have adopted their cousins. I know a family that adopted several of their cousins and are now siblings as well as cousins.

[Kelsey]

You share a same parent.

[Belly Boo]

omg this is really gross but my cousin got married to a cousin of his (hes my cousin by his mums side and shes his cousin by his dads side) and they had kids so their kids are cousins and siblings :/

[youdneverguess]

I fracking love that movie.

The answer is....you live in the deep south where there aren't a lot of options. OR your family is ugly and has no choice but to breed with one another.mmm

[john]

Yes, it is elementary, my dear Watson. It's called inbreeding. And is generally punishable by law outside of Nevada.

[i l o v e y o u]

Usually on facebook, people who are really close to eachother just list themselves as their siblings. i do that with my closest friends but of coarse, were not really brothers and sisters.

[i l o v e y o u]

Some pepole say people r there siblings if there really close like i had a friend who i was really close to and we were like sisters see on facebook people do that all the time

[William]

It's called incest - the marriage of (or at least reproducing with) close relations.

In the Facebook post you saw, the person's parents were brother and sister. In the song you are referring to, the man's father married his wife's daughter.

Note that divorce or widowing and subsequent remarriage can get around the legal problems that exist with this in most jurisdictions - in the song, the narrator married a widow, and then his father married the widow's daughter who was born before the narrator married the widow. Because of the legal entanglements, his dad is now his stepson-in-law -- making him his own grandpa.