In this article, I will explore the ethical concerns arising out of the use of preimplantation tissue typing (PTT) to create saviour siblings. There are two main ethical concerns about the welfare of the child to be born as a result of PTT. The first is whether the child to be born is treated as a commodity, as simply a means to save the life of his or her sibling. The second is whether the child to be born will be harmed as a result of PTT, either physically, psychologically or socially. These two ethical concerns reflect an individualistic approach to the welfare of the child, whose interests are treated as largely separate to the interests of other family members. I will argue that the welfare of the child born as a result of PTT should be conceived more broadly to include not only the child's individual interests, but also the collective interests the child shares with his or her family. I base this broader conception of welfare on the notion of human flourishing, which recognises that the welfare of a child is inextricably connected to the welfare of the intimate collective that is his or her family. The collective interests of intimate family members are particularly relevant in the context of PTT, as the members are engaged in a shared journey to save the life of an ill child.