Sherlock grew up too quickly because Mycroft was the preferred brother, and Sherlock thought that if he grew up quicker, his parents would like him more. This is why he likes being around children, because they remind him of the childhood that he never had.
The Childhood He Never Had
Sherlock grew up too quickly because Mycroft was the preferred brother, and Sherlock thought that if he grew up quicker, his parents would like him more. This is why he likes being around children, because they remind him of the childhood that he never had.