I think that it is very difficult to beat community building (even non-professionally, just in some spare time) by having children. There is also an exponential growth in the effect, and probably with a greater growth factor. Moreover, the similarity between you and your grandchildren is probably not that important, and it is very plausible to me that their effectiveness decreases sufficiently quickly so that it doesn’t even beat direct effects that you could have instead.
I think that it is very difficult to beat community building (even non-professionally, just in some spare time) by having children. There is also an exponential growth in the effect, and probably with a greater growth factor. Moreover, the similarity between you and your grandchildren is probably not that important, and it is very plausible to me that their effectiveness decreases sufficiently quickly so that it doesn’t even beat direct effects that you could have instead.