Maybe you grew so fast it left stretch marks on your legs. Or your voice started cracking every time you got on the phone. Or you hated needing to wear a bra. Growing up means going through puberty. It’s an integral part of becoming an adult. But we still don’t know how our bodies start the process.
Source: We Still Don’t Know What Jumpstarts Puberty
A lot of people point to hormones in meat, dairy & eggs for precocious puberty – especially in girls – I don’t think that’s been proven at all. But I have seen studies suggesting that girls without a father/father figure tend to undergo puberty earlier than those who do.