Odd Casting
At 24, Jean Simmons is a bit old to be playing a 17 year old, but that's not unusual in movies. However, it did strain credulity that they would cast Teresa Wright as her mother. Teresa is 11 years older than Jean and always looked young for her age. They tried to age her by not putting any makeup on her and making her as plain as possible but it just doesn't work.
Especially when you have Spencer Tracy as the dad, who was 52, why wouldn't you pick an actress in her 40s to play the mother?