Even considering the option of willing, consensual sex (which is legally impossible when under the age of consent), there is no basis in this case for assuming that's what happened. A horny kid with enough knowledge and understanding might go show off to his mates about having boned a mature lady. Not to a counselor that he'd had sex with his biological mother.
At 14 I was not willingly into having sex with a woman. I knew enough about sex, knew that I was gay and that I didn't sexually fancy women. Yet I'm pretty sure a woman could have made me horny, just about anyone could have done that. Leaving brute force aside (even though a 14 y/o boy is not necessarily stronger than a 30 y/o woman), kids are easier to control, especially by people who already have some, even if slight, authority status over them, and especially in unfamiliar situations.
Absolutely true that a lot of kids have sex before age of consent, especially when that's at 18. I did, and nobody ever got sued over that (and they also lowered the age to 16 as soon as I was 18...). So the law aside, it's not some static age, with kids feeling ready and knowing enough about what they are doing on a specific day. But it takes knowing what you want and what you're getting into. And if it's with an adult, it also takes a lot of responsibility, from both sides.
And in this case there was absolutely no responsibility from either. And unless that kid was aiming to get his mother sued, his reaction to the incident really points more to being totally unprepared and confused. Even nowadays there still are sheltered kids, maybe not ones thinking that erections are for peeing on fences, but clueless enough.
