Mid-parental height
Mid-parental height estimates a child's adult height from the parents' heights, adjusted by sex. Published by Tanner in 1970, it is a rough predictor with a wide honest range around it.
Example
With a 165 cm mother and a 180 cm father, the estimate is about 179 cm for a boy and 166 cm for a girl — each carrying roughly ±8.5 cm at two standard deviations.