In a hospital maternity ward there are only five babies. Baby 1 is heavier, with red hair. Baby 2 is male and thin, with the same colour hair as Baby 3, who is blonde and wears a bonnet. Baby 4 is one of the three female babies and Baby 5 wears sunglasses and is heavier. All babies wear bonnets and at least one of the females wears sunglasses.
A thin, red-haired baby wearing a bonnet is the oldest of the group. Who can it be?