20%
 

I've read that as high as 20% of children's fathers are not biologically their fathers.

My first wife was basically a cold fish. She was on the pill from when we first got together. During one period of time, after we had been together for a couple of years, her doctor pulled her off the pill for some medical reason. In the couple of months she was off the pill, she was horney and orgasmic. We didn't get pregnant, and when he put her back on the pill she became a cold fish again. So, I didn't make her pregnant, but the possibility of getting pregnant sure changed her behavior.

Or maybe the hormones in the pill made her lose her desire. That is a real thing for some woman. If you aren't going have kids and there isn't a medical reason for her to be on the pill, try getting a vasectomy and take her off the pill.

We were young, early 20's, planned on having kids later in the marriage, hence the pill as a birth control method. This was back in the 70's, so a lot of side effects of the pill wasn't known. Marriage didn't work out, partially because of sexual mismatch, partially for other reasons, thankfully we didn't have kids. Second wife was always horney, pill or no pill, but she was more than a little crazy. In any case, pregnancies were on purpose, and fun to cause.

Or try out a few different brands of pills - they are different.

This is one of those ideas where the fantasy is better than the reality.