At what age do children become aware of parents having sex?

[Artmumcreative]

We have an eleven month-old who sleeps in the same room. We wait until she's asleep to have sex and stop/resettle her if she stirs/wakes.

Is there any research about when children become aware that their parents are/have been having sex? If not aware, what's the earliest an older child/adult can remember (e.g. my earliest memory was when I was two or three)?

Our youngest shared a room with us until age 4. We stopped having sex with him in the room at about age two and used to have living room floor sex before going up to bed for a couple of years.

Our intimate relationship died off for myriad reasons, but parenting wasn’t one of them.

The youngest in question is now a tween. We were discussing Adolescence in the car the other day and I had to explain the meaning of Incel. Not only was a revelation that his parents had had sex since his conception but he assumed this new word, celibate, applied to his mother.

Regulars on this board will know that is laughable but I did not disabuse him of that notion!