Learn English – Hypernym for “input” and “output”

The phrase I would use is 'like two peas in a pod'. It's used in both British and American English, and keeps the plant theme.

Strict is a good choice:

• strongly limiting someone's freedom to behave as they wish, or likely to severely punish someone if they do not obey:
  • My parents were very strict with me when I was young.

Cambridge Dictionary

From: It is good to be a strict parent:

• As a child, I always wondered why there are different kind of parents. Every parent has a different kind of attitude towards their children. Some are strict and some are equally opposite in strictness. It is always best to be a strict parent because a child’s mind is always directed to do appropriate things and this prevents child from distracting to wrongdoings.

From: Expository Essay on Why Parents Are Strict:

• There is a question on whether parents should be strict or not, and how strict they should be. If a parent is strict, many tend to think that such parents are always unfair to their children, but these parents tend to think that the best parents are strict.

Ngram: strict vs stern vs severe parents.