Parashas Vayeishev · Passuk 37:2
These are the generations of Yaakov: Yosef, being seventeen years old, was feeding the flock with his brothers; and he was a lad with the sons of Bilhah, and with the sons of Zilpah, his father’s wives; and Yosef brought their evil report unto their father.
Torah Temimah points to Avos d’Rabbi Nasan, chapter 2.
Sefaria — Avos d’Rabbi Nasan 2
English: Was it not fitting to say “These are the generations of Yaakov — Reuven”? Why does it say Yosef? Rather, just as Yaakov was born circumcised, so Yosef was born circumcised.
Derash on the verse (midrashic sugya) — not a formal named middah of the 13. The unexpected naming of Yosef instead of Reuven is explained by a parallel physical trait.
The verse begins the generations of Yaakov with Yosef rather than Reuven because both Yaakov and Yosef were born already circumcised.