Based on parents
A rough rule for any child is as follows:
take the dads height
less 5 inches + moms' height then divide the sum by 2 = expected final height for girls.
Take the moms' height + 5in & add to dads, then devide the sum by 2 to get expected boys final height. This produces an estimate pediatricians use to decide what growth pattern to expect. This is not exact but gives us an expected range.