Leona asked when we'd capitalize "dad":
In direct address ("Dad! It's Father's Day! I'm taking you out for ice cream!"), you capitalize "dad"-- when it's a name substitute, and a name is a proper noun (name or title) and capitalized.
But with "his dad" and "my dad", "dad" is a substitute for the common noun "father," so no cap.
Just depends-- it's the usage that matters, not the word. If it's used as a way of addressing someone, as you would use a name or nickname, capitalize.
This website has information on correct use of capitalization.