Girls hitting puberty earlier? Is milk to blame?

So, yes-or-no question: Does starting puberty earlier mean that, in general, children will have more advanced brain development than peers of their same age from years past? (like parents)

Your brain develops with age also. Not just puberty. Puberty only develops certain parts of the brain like the hypothalamus, the pituitary, the gonads, the adrenal glands, and your hormones.