There was a video about this posted a bit ago. The speaker said basicly this same thing. After the age of 7, the environment that your kid is placed into, and the other people they are around, has for more influence on them that the parents have.
You do your best for the first 7 years, and then you do your best to find the right environment for them for the rest of their lives.
Reposting is a long standing tradition on Reddit... I don't see a reason that should change on Lemmy.
It's not just a question about memes. If you see content on Reddit for your favorite topic or game, you should 100% replicate that data over to Lemmy.
If there's a good duplication of content in both places, it makes it easier to move completely over to Lemmy.