Also 18 and 19 year old's flying modern jets
Age is not a factor, however maturity is.
The younger students and subsequent qualified pilots are mostly from the Integrated schools as the modular students are generally older and have taken longer to reach their goal.
If at the youngest age to hold a professional licence (18) you can pass the airline selection procedures then there is no reason why they wont take you.
Also ageism is against the law.