This article explores how Thai culture, gender and age influence sex education in Thailand, and how online sources and social media have emerged as an alternative source of sex education among young people. Qualitative data was gathered by means of in-depth interviews and focus group discussions from 99 young people aged 15-24 years of various genders and sexualities living in Bangkok. Age and gender/sexuality have a powerful influence on how students perceive sex education in Thailand. Younger people of all genders/sexualities were interested in the changes occurring in puberty and defining their gender/sexual identity, while older informants were more interested in sexual health issues including prevention and self-assessment. With respect to sexual relationships, different genders/sexualities showed varying interests, some were interested in the emotional aspects, while others were more interested in the physical dimensions of sex. Overall, Thai culture constrains the success of sex education by limiting learning opportunities and discussion, and by the provision of inauthentic knowledge to students. Online sources and the social media offer possible solutions to these inadequacies in sex education.