yes in the comics Alex Summers/Havok is Scott Summers/Cyclops's younger brother but not in the films they are still related but in a different way that works for the films

His real name is Scott Summers and he is the brother of Alex Summers aka Havok from X-Men First Class.

Philip Summers (grandfather), Deborah Summers (grandmother), Christopher Summers (Corsair, father, deceased), Katherine Anne Summers (mother, deceased), Alexander Summers (Havok, brother), Gabriel Summers (Vulcan, brother), Jack Winters (Jack O'Diamonds, former foster father), Jean Grey-Summers (Phoenix, wife), Madelyne Pryor-Summers (ex-wife, deceased), Nathan Christopher Summers (Cable, son), John Grey (father-in-law, deceased), Elaine Grey (mother-in-law, deceased), Sarah Grey-Bailey (sister-in-law, deceased), Aliya Jenskot (daughter-in-law, deceased), Tyler Dayspring (Genesis, grandson, deceased), Stryfe (clone son, deceased)

Donna Summer has 5 sisters and 1 brother.

Nick Joe and Kevin Jonas have a third brother named Frank