Maybe one reason you keep going back to the same family is precisely because you've been playing them for so long, and a part of you goes into them. I know it's like that for me.
It's not a family I'm attached to, but rather just my two "main" Sims. If memory serves, they've been around since 2016, and I still could never bear to let them go. In fact, they've been with me through university, which was a challenging period that saw me move to another country. Now that I'm home and I've started work, they've come back with me too.
They've lived many different lives - David here has gone from lifeguard to firefighter....
https://i.imgur.com/Bvan4sX.jpg
https://i.imgur.com/Ir3cLPy.jpg
Whereas Martin has gone from forensic scientist, to self-employed painter, to doctor....
https://i.imgur.com/kooOIu8.jpg
https://i.imgur.com/TpCSlz2.jpg
The other thing about sticking with the same Sims for long periods is that my headcanons about them (i.e. how I imagine their personalities, likes/dislikes etc) have developed over time. And this only makes me more attached to them since they've started feeling more and more like real people.
Maybe others can relate? :)