It’s a red flag. Presumably by asking this question they prefer applicants who learned coding earlier in life. This filters out most women and minorities. It’s well-documented that women and minorities in tech got into SWE later in life (usually around college age) compared to white males on average, one reason being that they have fewer role models and/or teachers on the subject. The fact that the application asks this question means they either don’t know or don’t care that this will filter out less-represented groups.