I've seen many family members naked including my father, cousins and uncles. All of them except my dad, had big soft penises at least 5", 5.5". I have seen most of their hardons by comparing together and morning wood when sharing beds and rooms and they are at least 7" and over with one cousin having 7.5". Dick size talk come up frequently from jokes and stories shared of prior experiences with friends and girls and outright comparing.
Mine hangs 6" soft and is 8" hard and my dad and me have a close relationship to talk size and have general sex conversation. My parents raised me naked and so I had seen him daily and when he is soft it barely peeks out and his hard is under 5". He has seen our relatives and been around at times my cousins and uncles have had those talks and we don't know how he got the short stick.
He goes between jealous and proud of mine, but even now it does bother him a bit. He got teased growing up over his small size and being uncut, and since I outgrew him fast it had brought that feeling of envy back. Plus at family gatherings where guys are in a nude setting together, him being the only one small has embarassment creeping in for him.