When you're young, if you're making comparison, they're probably either to only a few different people - like your Dad, maybe your best friend, maybe a few guys you've seen in passing in the restroom - when the range of penis size varies enough that to get realistic ideas about it, we've got to be looking at more than just a few penises.
One typical reason is that younger men will often have unrealistic ideas about penises. While many statistics show that around half of all cis men are dissatisfied with their penis size (despite the fact that their partners don't feel the same way), with younger men it often seems even more common. Throw a rock at any sex education site or service, ask what the most common question we get is from people who identify as men and we'll all tell you - with an air of exhaustion, mostly because we get asked it so often and it's so clear to us how these worries hold men back from feeling good about themselves and their sexuality, as well as how they often negatively impact sexual relationships - that it's about penis size.
