Everyone Must Drink at Seder

At the Passover seder, all Jews above the age of bar mitzva or bat mitzva (including women--unlike on other Jewish festivals) must drink wine for kiddush and for the other three times in the seder when the borei pri ha'gafen blessing is said.
Note On the other Jewish festivals, only one person needs to drink the wine when kiddush is said, and that will cover and fulfill everyone else's requirement for that kiddush.
Note Only children and people who will get sick if they drink alcohol are permitted to drink grape juice at seder.