Had he been over 18 at the time, Ingram could have faced 14 years but instead he could only be handed a maximum of five years.
Ingram, from Kent, has now been jailed for three years after pleading guilty to 13 offences dating back to 2015.
Ingram admitted 12 counts of sexual activity with a child and one of causing a child to watch pornography.
Joshua Ingram told the victims he wanted to "f***" them and demanded they "better keep their mouths shut" about his crimes.
It comes just weeks after his dad John Ingram was sentenced for marrying his 16-year-old stepdaughter while wed to her mum.
20(1).webp?trim=37,0,8,0&quality=75&auto=webp&width=1000)
