Pools that are designed for swimming laps need to be much deeper than a standard pool. 1.2 metres will give swimmers enough space to swim laps comfortably without touching the bottom. If you’d like to let people dive in the pool, the deepest area should be close to 2m.
If pool is mainly being built to share memories with your new babies, then a shallow pool is the way to go. Start it really shallow like 0.3m and have a gentle gradient to the deep end. Remember kids do grow up so think ahead!