I have a 13 yr old sister.her dad is 5'9 and mom is 5'3.she is 5'3.how much do you think she is going to be?

Hard to say: The final height of a female is estimated as 1/2 their parents combined height less 2.5 inches,+/- an inch.It is influenced by when they had their first menses & prior growth rate.Using the parental data supplied she isclose to her predicted height of 5'3.5". Most stop growing within 3 yrs of their first period.An x-ray of her hand could be studied for bone maturity, if delayed she could grow more