Children and citizenship

Hello!

I'm reading up on the path to citizenship after 5 years residency etc. I am a little confused though so maybe someone can help clear it up! My family (husband, myself, and 3 year old) plan to move to Portugal on the D7 visa. If we stay and become eligible for citizenship after 5 years...does our son also have eligibility? The web seems to say you must be 18. Is that right?

Thanks!