[1] Trazegnies is of Quechua descent through the Vásquez de Velasco, his maternal family, which was a topic of conversation between his father and writers José de la Riva Agüero and Raúl Porras Barrenechea.
The origin of this branch is believed to be that of Inés Huaylas Yupanqui, the daughter of Huayna Cápac.
From 1964 to 1965 while pursuing a doctorate degree, he studied philosophy of law at the Sorbonne University, where he was a disciple of Michel Villey.
Upon his return in 1973, he founded his own law firm De Trazegnies & Trelles and reincorporated to the Catholic University.
In this capacity, de Trazegnies negotiated the Brasilia Presidential Act which put an end to the conflict in 1998.