Answer:
The sins are that both Don Pedro and Don Diego were attracted to Don Juan, in addition to not being concerned with his virtue.
Step-by-step explanation:
Don Pedro and Don Diego had the responsibility to care for and repair the moral defects that Don Juan had, especially in relation to his highly sexual behavior. However, neither was interested in fulfilling his obligations and encouraging Don Juan to improve his behavior because they were attracted to him and decided to fulfill their wishes, believing that what Don Juan did was something intrinsic to the youth and that should be explored.