 [ Symptoms ] does feeding rice cereal make baby gain weight  5 month old spoon fed [ Disease ] there are a couple of ways to predict adult height for toddlers the simplest way is to double the child is height at age 2 another trick is to look on a gender appropriate growth chart for the child is height percentile at age 2 and then look at the height for that same percentile for age 18 years lastly for boys you can add 5 inches to the mom is height and then average that number with the dad is height for girls you have to subtract 5 inches from the dad is height and then average it with the mother is height