In this paper, we explore the ethical and legal implications of a hypothetical use of artificial gametes (AGs): that of taking a person's cells, converting them to AGs and using them in reproduction-without that person's knowledge or consent. We note the common reliance on genetic understandings of parenthood in the law and suggest that injustices may arise if unwitting genetic parents are sued for child support. We draw parallels between the hypothetical use of AGs to facilitate unwitting parenthood and real examples of unwitting parenthood following cases of sperm theft. We also look at the harm that might be caused by becoming a genetic parent, independently of financial obligations, and ask whether such harm should be understood in terms of theft of property. These examples help to highlight some of the current and prospective difficulties for the regulation of genetic and legal parenthood, and show how existing regulatory assumptions are likely to be further challenged by the development of AGs. We conclude by suggesting that the reliance on genetic connections to generate parental responsibility (financial or otherwise) for offspring is flawed and that alternative ways of establishing parental responsibility should be considered.