What's the difference between a first cousin once removed, and a second cousin?

A person with whom you share a grandparent (but not a parent) is a first cousin; someone with whom you share a great-grandparent (but not a grandparent) is a second cousin.

The child of your first cousin is your first cousin once removed.

I don’t understand all that 2nd, 3rd removed bull..

second cousin
Noun
the child of one’s parent’s first cousin

first cousin once removed
noun
A child of one’s first cousin; a first cousin once removed.

Source

The degree (first, second, third cousin, etc.) indicates the minimum number of generations between either cousin and the nearest common ancestor.

The remove (once removed, twice removed, etc.) indicates the number of generations, if any, separating the two cousins from each other.

I don’t know, but you probably shouldn’t marry either of them.

Darwin has it right. Not to insult anyone here, but it always amazes me how confusing this is to people. About half the people I talk to about it can’t figure it out. I think it’s really easy once you get the concept.

My mom’s 1st cousins are my ‘1st cousins once removed’. Their kids are ‘my second cousins’. Does that help?

Here is a chart that might help: http://en.wikipedia.org/wiki/File:CousinTree.svg

you can make out with a second cousin without too much retribution?

The (number) cousin is the number of generations away from the common ancester.

Gen A Common ancestors lineage parents
Gen B,,,Sibling 1…..........Sibling 2
Gen C…1st cousin 1….......1st cousin 2
Gen D…2nd cousin 1….......2nd cousin 2
Gen E…3rd cousin 1….......3rd cousin 2

The relationship between GenC1 and GenD2 is 1st cousin once removed.
The relationship between GenC2 and GenE1 is 1st cousin twice removed.
The relationship between Gen E1 and GenE2 is 3rd cousin

@bigbanana Third cousin is better. You only have 2/16th common ancestry.

@essieness I don’t recall where I saw it—it was so long ago—but it said that there is really no genetic problem having kids with a first cousin. It’s just full siblings where it’s a problem.

That chart doesn’t seem correct…when referring to your parents cousins, those are your second cousins. I’ve never heard of them being called your first cousin once removed then their children are second cousins…that’s not right.

My cousins are my sons first cousin once removed, because he’s once removed from me.
My second cousins are my mother’s cousins children. Hmm, so I guess that would make my mother’s cousin’s once removed. I was wrong. Okay.

@essieness There isn’t any medical problem with siblings if there are no gene based conditions either. The closer the relationship, the more likely problems are going to be passed on. The modern prohibition is more a cultural/psychological one when genetic testing can tell if there might be problems.

@galileogirl – you know I read somewhere that 2/16ths is the same thing as 1/8th.
;-)

I was going by common ancestors, see my chart above, genealogy terms rather tha straight math reduction. But maybe you aren’t a genealogist <:}

@daloon and @galileogirl But still… LOL.

I know but the Ick factor is cultural, It worked for the Pharaohs.

Well, I am not and would not be interested in my sister, but there was this not-so-distant cousin who had the hots for me…. I turned her down, partly because of that ick factor.

@casheroo 2nd cousin can be 1st cousins once removed. I’ve been doing genealogy for 35 years. Trust me.

I dont understand it myself.