Short fingers age 15?

my mums fingers are a bit longer than mine and my dads are huge. but i take after my mum (height, looks e.g) are my fingers finished growing or will they continue until i am 18? it is annoying on the keyboard i could barely reach one octave then i kept stretching and i could in the end, but my other fingers are annoying and are too small. Any exercises to make them grow?