Speaking about breastmilk, I have two parents, four grandparents, eight great-grandparents, and sixteen great-great-grandparents. (Of these people, only two are currently alive, but I'm counting all the rest because they are genetically significant.) In this specific respect I am entirely normal.
One side of my family is Muslim, and marriage between first cousins is considered acceptable - although these days it's fairly uncommon. One of my uncles (codenamed 2) married a first cousin, my aunt (codenamed 2+). They had three daughters (codenamed 2.1, 2.2, and 2.3), all of whom are top scholars in Hong Kong and currently pursuing successful medical careers. None of the daughters has shown any sign of genetic problems arising from consanguinous parenthood. The middle daughter has unusually pale skin but this has been seen as a cosmetic benefit by the rest of the family.
This same cousin (codenamed 2.2) is of particular interest to me because she is extremely attractive and good company and seems to be quite happy when I'm around. She's also very liberal with hugs and cuddles and kisses and she doesn't have a boyfriend as far as I know. Hanging out with her I got the sense that it could end well for everybody involved.
HOWEVER IT COULD ALSO END POORLY FOR EVERYBODY INVOLVED
Before things got out of hand, I decided to sit down and draw a family tree to determine how many ancestors we have.
[th]Individual[/th][th]Parents[/th][th]G'parents[/th][th]G'G'parents[/th][th]G'G'G'parents[/th] Bing (son of unrelated parents) | 2 (par) | 4 (par) | 8 (par) | 16 (par) |
2.2 (daughter of first cousins) | 2 (par) | 4 (par) | 6 (-2) | 12 (-4) |
Antichrist (spawn of Bing + 2.2) | 2 (par) | 4 (par) | 6 (-2) | 10 (-6)  |
My cousin (2.2) is the daughter of first cousins and she has: two parents, four grandparents, but only six great-grandparents - which is two fewer than normal. This is the inevitable byproduct of her parents (2 and 2+) being first cousins themselves.
If this cousin and I had a kid (codenamed "Antichrist" for brevity) the kid would have: Two parents (par), four grandparents (par), six great-grandparents (two under par), and ten great-great-grandparents (
six under par). One generation further, and the kid would have twenty g'g'g'parents, or
twelve fewer than a normal kid.
This gives rise to the "Kissing Cousin Paradox":
1. There are a few reasons why you totally should.
2. ...and there are a significant number of reasons why you absolutely should NOT.
To me this is an eloquent distillation of the tragedy of the human condition, fallen from grace.
I believe I shall have to be especially devious here.