I'm 25, almost 26. I don't lie about my age, because people don't believe me in the first place.
I've found that it's easy to remember my family's ages. My oldest brother is 1 year younger, so that's easy. My middle brother is a bit harder, being 14 years younger. My dad is exactly 20 years older than me, and my mom is 20 years older than me or my brother, depending on the time of year. My husband's mom was born in 1950, and his dad is exactly 10 years older than my dad - give or take 3 days. It's my husband's age that gets me confused sometimes! 3 1/2 years older, and it has a tendency to throw me off.