Breakdown of Þeir sakna hefða sinna.
þeir
they (m)
sinn
his/her/their own (reflexive possessive)
sakna
to miss (feel longing for)
hefðin
the tradition
Questions & Answers about Þeir sakna hefða sinna.
Why do we use sinna here instead of þeirra?
Sinna is the reflexive possessive pronoun meaning "their own". Because the subject (þeir) is missing their own traditions, we must use the reflexive form. If you used þeirra, it would mean they are missing other people's traditions.
Why are the words hefða and sinna in the genitive case?
The verb sakna (to miss) always takes its object in the genitive case. Since the noun being missed (hefða) is forced into the genitive, the pronoun describing it (sinna) must also be in the genitive to agree with it.
Does the form sinna change depending on the gender of the noun?