Boundaries with family — parents, siblings, in-laws — feel hardest to set. The relationships are durable; the people aren't going away. The instinct is to absorb whatever cost rather than create friction. Cumulative cost over years is usually higher than the friction would have been.
What family boundaries look like
Limited phone availability ('I'll call on Sunday'). Visits with end times. Topics off-limits (politics, weight, relationship status). Not engaging in family drama you didn't create.
Initial pushback is universal. Consistency over months usually produces adjusted relationships rather than ended ones. The relationships that can't adjust often weren't healthy to maintain anyway.