I was looking for a quote to describe paternity certainty more fully, but didn't find one while I was writing above. Here's David Buss and David Schmitt's description...
"Given the tremendous effort that men sometimes expend for their children, we expect that natural selection would not produce men who dispensed it casuallly or indiscriminately... The sexes are asymmetrical in probability of parenthood. Because women, like all other mammals, conceive internally, theere is never any doubt about their parenthood. Maternity is 100% certain. Men can never be entirely sure. Because ovulation is concealed, or cryptic, in women, a man would have to sequester his mate for a period of months to be entirely sure. Even the, he has to sleep sometimes, and this opens the window of possibility of alien insemination."
From Buss & Schmitt (1992) Sexual Strategies Theory: An Evolutionary Perspective on Human Mating. Published in Psychological Review.
Male, Straight, Poly
“Instead of getting better and better at avoiding, learn to accept the present moment as if you had invited it. And work with it instead of against it. And making it your ally rather than your enemy.”