Why do i keep crying over childhood memory songs?

I'm 18 and i grew up in the 90's a lot of songs that make cry are all songs that came up in the 90's like All The Things by Joe. really makes me cry because it reminds me of my mom when she used to play his songs when i was really little. i have realy good memory. They Don't Know by Jon B Touch Me Tease Me by case && foxy brown, I Wanna Be Down by Brandy. Lauren hill, Blackstreet Again by Janet jackson all of those artist and songs remind me of the 90's. && how things were different back then. i miss it very much. It seems like times were happier back then everyone was younger, music was wonderful. Most of those songs remind me of my mom when she was in her twenties in the early and late 90's. Today she's older im older. things are a lot different. moving from place to place. Although she is kindve the same a little bit.