Brazdeikis was born in Kaunas, Lithuania, to Diana and Sigitas "Sigis" Brazdeikis. He has an older sister, Ema. His second aunt, Lina Brazdeikytė, is a former professional basketball player who won the EuroBasket Women 1997 with the Lithuania women's national team. His family emigrated to Chicago before moving to Winnipeg and Etobicoke before settling in Oakville, Ontario.