Alba was born in Pomona, California, to Mark Alba, who is Mexican American (though both of his parents were born in California),and Catherine (née Jensen), who has French and Danish ancestry; the two married while in their teenage years. Her maternal grandfather was a Marine NCO for 30 years, serving in the Pacific during WWII, and later as Asst. Drum Major for the United States Marine Band. Alba was raised in an Air Force family, along with her brother, Joshua (an actor who appeared with her in the season one finale of Dark Angel), and her grandparents, until she was seventeen years old. Her father's Air Force career took the family to Biloxi, Mississippi and Del Rio, Texas, before they settled back in California.
