@sun depends on the age gap, the bigger it is the nicer the experience.
my sister is 13 years younger than me, my parents decided to take a date vacation by themselves (we stayed at our aunts house for a week) one day and BEHOLD: suddenly out of nowhere for no reason my mom is pregnant.

really, if the age gap is small you WILL argue all the time with each other, kicking and screaming and everything.

but my second sister is much younger than me and is extremely sweet, i essentially act as a second male role model