Study question Is age a key criteria for characterizing the experience of families in telling donor offspring about the facts of their conception? Summary answer The study shows that, although donor offspring’s age at the time of disclosure has an impact, it is insufficient to describe these families’ experiences What is known already Secrecy was the norm for decades in donor conception, but “openness” has now become the new core value for institutions, professionals and interest groups. Accordingly, in recent years information-sharing practices have shifted in donor conceived families, but a proportion of parents, especially heterosexual couples, still appear to not inform their children about their being donor conceived. Disclosure recommendations seem difficult to apply in practice. A recurring question is: when should children be told? Age is presented as a key criteria: the younger the children are when their conception story is shared, the less of a problem it would create. Study design, size, duration The qualitative social science study includes two sets of semi-directive interviews conducted with 20 French sperm donor conceived adults (April-Dec. 2019) and 22 French parents by sperm, egg or double donation (Feb.-Oct. 2020). Calls for interviews aimed at donor conceived adults and parents by donation were shared on the Internet, in the media (press, radio, television) and through interest groups (PMAnonyme, BAMP!, MAIA) in France. The contact initiative was left to potential participants. Participants/materials, setting, methods Donor conceived participants include 17 women and 3 men conceived 1960–2000 through anonymous sperm donation in heteroparental families. The parent participants include 20 families (20 mothers, 2 fathers) who used donor conception—mainly anonymous (19)—in France, Spain and the Czech Republic starting in the 1980s. 17 conceived as heteroparental couples, 2 as solo-mothers-by-choice and 1 as a same-sex couple. 17 have already informed their offspring of the facts of their conception. Main results and the role of chance The participants’ experiences of disclosure appear to be bound to their historical and social context, especially regarding the prevailing norms on secrecy. Older parents mention having been advised by clinic professionals to keep the facts of their conception from their child(ren). Some also feared the stigma related to infertility. In contrast, some younger donor conceived participants recall the use of a children’s book while being told of their conception as toddlers. Beyond age, the larger context thus affects information-sharing practices. Furthermore, experiences of disclosure are impacted by the family context and history. Some are embedded within larger events such as divorces or the death of a family member. The story of the donation may be linked to narratives of diseases (such as cancer) or traumatic events (such as the loss of a fetus in utero) that may prevail over donor conception or make it untellable. Age proves to be an insufficient criteria to qualify these experiences, all the more so since “disclosure” sometimes unfolds in several steps. Some parents have first talked about their fertility issues without mentioning the use of a donor. Behind the prevailing norm of “openness”, difficulties in actually disclosing are confirmed. Limitations, reasons for caution Being qualitative, the study only includes a small number of participants without claiming exhaustivity nor representativity. It imperfectly reports on the view of those who do not disclose, as all participants question the principle of secrecy, many being members of interest groups defending openness. Wider implications of the findings: Our results complement existing studies that emphasize the weight of age in donor conceived families’ experience regarding disclosure. Age alone cannot describe information-sharing practices that are embedded within their historical and social context as well as the family context and history. Results thus inform familial difficulties related to disclosure. Trial registration number Not applicable