Romantic and sexual networks of adolescents

Epidemiologically speaking, it is crucial to understand the contact structure through which disease travels. In studies of sexually transmitted diseases (STDs) in particular, the structure of sexual networks is critical for understanding STD diffusion. Generally, the network structures of disease diffusion and infection can be categorized into four types: the core infection model, the inverse core infection model, the bridging model, and the spanning tree model (see below).

Disease diffusion is widespread among adolescent populations. A study mapped the romantic and sexual relationships of an entire high school population of over $800$‍ adolescents in a midsized town in the Midwestern US for a period of $18$‍ months. Students were asked to identify their sexual (not dating) and romantic partners (dating) in the past $18$‍ months from a roster of other students attending their school. The study found that adolescent sexual networks are structured very differently from adult ones. In an adult sexual network, there is normally a core group of very sexually active people that links out to others. This can be envisioned as a transportation hub system where many points are connected to a small number of hubs. At the high school, on the contrary, there was no core group. Instead, the romantic and sexual network at the school created long chains of connections that spread out through the community, with few places where students directly shared the same partners with each other. This can be comparable to rural phone lines that run from a long main line to individual houses. One single component of the network was found to have $288$‍ linked students, in one long chain. This chain featured $52\mathrm{\%}$‍ ($288$‍) of the romantically involved students at the high school, but most students had only one partner and they had little idea of their connections to the long network chain.

Adapted from Bearman, P.S., Moody, J., & and Stovel, K. (2004). Chains of Affection: The Structure of Adolescent Romantic and Sexual Networks. American Journal of Sociology. 110 (1), 44-91.