Is the questioner absolved of responsibility if his parents withdraw usurious interest from his account and deposit it into his siblings' accounts, knowing that the money originally belongs to the parents but is in the questioner's name to secure his future?

As long as the money is a gift and you have not taken possession of it, you do not own it. Consequently, there is no sin upon you for its presence in an interest-bearing account; the sin lies with your parents because they still own it. If you take possession of it in the future, you must withdraw it from the interest-bearing bank and spend the usurious interest on charitable causes or for the poor and needy. Giving it to your brothers is not sufficient unless they are poor.