People usually become Senior Engineers in their late 20s, if not mid 20s. It's the fakest job title in the industry. The majority of Senior Engineers are probably age 28-40 - common ages to have young children.
"Senior" really just means "this person is not straight out of college." It doesn't actually mean senior in the same way that Intel and AMD's "2nm process" technology does not actually correspond to any physical dimension on the die. It just means you have some type of experience.
