On the 1851 census Christina was noted as born 1823 Kingussie, Invernessshire, which is where her marriage took place to Angus McBain in 1849. Their son William was born there in 1851, the step children's surnames were McKay & Fraser.
In 1861 the wife of Angus is noted as Margaret McBain, two of the children from 1851 are present noted as son & daughter but the details vary. There are 3 children present born after 1851, including a Christina.
I cannot find a birth record for Christina in Perthshire or Invernessshire. Therefore no details to work on for her parents.
Colin