A. The clue is in the knot by the hand-tefillin, not the straps themselves. Most Sephardic Jews and Chassidim wind their Tefillin arm straps outward, while most non-Chassidic Ashkenazic Jews wind their arm straps inward. The inward or outward wrapping style is connected to how the knot is designed. As your grandfather was from Eastern-Europe and these Tefillin wrap outward, he was probably from a Chassidic community.