It is widely recognized that traditional informed consent requirements are highly problematic in the context of population-based genetic research. This article is based on a qualitative study that describes and analyses the consenting procedures and perceptions of donors to the North Cumbria Community Genetics Project (NCCGP), a DNA bank in northwest England. The NCCGP collected placenta and cord tissue, as well as maternal blood samples and health and lifestyle information, in order to conduct genetic epidemiological studies. The findings show that the nature of the sample (i.e. afterbirth) significantly impacted donors’ decision to donate. The antenatal context also influenced the way the request was framed to potential donors, who had a limited understanding of the aims of the biobank. However, the article concludes that a lack of understanding on the part of donors is not necessarily an ethical problem and that efforts to re-think informed consent guidelines may benefit from paying greater attention to the factors that motivate people to donate in the first place.