Wozniak / Tometchak - Were my grandparents Jewish?

My grandparents left Poland in 1914; his last name was Wozniak and hers was Tometchak...what is the chance that they were Jewish?

very little

No-one can say solely on the basis of that information. Jews were known to take on on the names of the countries in which they lived. The two you listed are perfectly good Polish names.

WO-NIAK: patronymic tag for the son of the woźny (court crier) or woźnica (carter).

TOMCZAK: patronymic tag for the son of Tomasz (Thomson).

0.99%

To be jewish, you haft to have 3 jewish grandparents, or be half.

Anything less is mischlinge. One jewish grandparent, and 3 gentile grandparents is grade 2.

Mischlinge were denied titles and positions. They retained there citizenship.