Due to his mother's views, Leonard never celebrated his birthday or Christmas when he was a child, and when she visited him she was not impressed with his unoriginal research. Leonard revealed to Penny that he built a " hugging machine " when he was young in order to compensate for the lack of affection from his mother. He further stated that his father used to borrow it. Beverly also belittles Leonard by pointing out that his brother and sister are more successful in their respective fields than he is. Leonard's brother, Michael, is a Harvard law professor and is engaged to the youngest appellate court judge in New Jersey history (and has since gone on to work with a Habitat for Humanity -esque organisation), and his older sister, whose name is unknown, is a cutting-edge medical researcher working with gibbons to cure diabetes. However, Beverly admits in season 11 that Leonard married the best out of his siblings, after she develops a genuine friendship with Penny. Leonard also dislikes his memories of Christmas, not just because he never celebrated it, but also because instead of gifts the Hofstadter kids had to turn in papers to "Santa" which were graded the next day. Over the course of six years, he never got over a "C minus", which according to Sheldon was a true gift, because by Sheldon's lights he never deserved anything better. After the episode "The Peanut Reaction", Leonard likely begins celebrating his birthday after Penny throws him a birthday party after hearing that he had never had one; this is evidenced by Leonard asking Brent Spiner to come to his birthday party at the end of "The Russian Rocket Reaction". As for Christmas, Leonard has come to love it as an adult, unlike Sheldon. Leonard had two childhood pets, a cat named Dr. Boots Hofstadter and a dog named Mitsy. Near the end of season 12, in "The Maternal Conclusion", Leonard's mother seems to be more supportive of her son's new job as co-lead of the University's Photon entanglement project, even spending time with Leonard as he shows her around his new laboratory. However, she reveals that she is doing research for her new book that highlights her parenting technique although difficult most of the time, directly resulting in the success of her children. This deeply upsets Leonard and Penny who thought that Beverly was making a genuine effort to better their mother-son relationship. Leonard finally confronts his mother, telling her of the many ways she has hurt him. After calming down, Leonard tearfully forgives his mother and himself for the emotional toll he has carried for most of his life. Beverly thanked her son for forgiving her and hugged him thus seemingly repairing their relationship.