What about music? Would this be hothousing as well?
Both of my kids started formal music lessons before the age of four. Both wanted to do it. The first one because he saw some kids playing and thought it will take him A LESSON to play like that, the second one because her brother was doing it (she actually got her first violin for her second birthday because she was dragging and damaging mine). At first they wanted to practice, but after a few months it became, and is to this day, a chore. I have always made sure they did they daily practice, bribing them when they were little, making sure that their schedules are not hectic right now, as they are older.
So this can also be categorized as hothousing. But I do not think there are many musicians that were practicing their instruments at 13 years old for a couple of hours a day and loving it. Do not get me wrong,they LOVE to play. Practicing is different.
Did you know that Beethoven's father was spanking him as little Ludvig refused to practice :-) We are a different society now, but maybe if it wasn't for that spanking we would not have the 9th Symphony (my personal favorite :-)