As technology increasingly becomes a way access to essential services and social participation, HCI research has a fundamental responsibility to ensure digital equality and social justice across all user groups. While the field has made significant progress in understanding and incorporating gender as a social construct, leading to more inclusive design practices, the treatment of age in HCI remains largely embedded in chronological, binary concepts. Through a comparative analysis of literature in HCI on gender and ageing we identify key parallel factors in their social construction including socialisation, media representation, stereotypes, language use, and institutional frameworks. We demonstrate how these parallels can guide the evolution of age-related research and design in HCI, moving beyond simple chronological categorisations toward more nuanced, intersectional approaches. This new understanding of age has the potential to lead to more inclusive technologies that better serve users across all ages.