In pre-colonial Ireland, children would be sent to other parents for a few years to give them a different household and perspective. See here and here. Cú Ċulainn ⁊ Ferdia were famously foster-brothers.

The word ‘oideaċas’ (‘education’ in English) is now a common word, e.g. ‘an Roinn Oideachais’ (‘Department of Education’)

Interesting that that comes from ‘oide’ meaning a ‘foster father’, figuratively a teacher.

What a lovely culture we have, seeing the Gaelic traditions leaving their traces on us.