Complex sentence: Gluck was born into a wealthy Jewish family in London, the child of Joseph Gluckstein, whose brothers Isidore and Montague had founded J. Lyons and Co., a British coffee house and catering empire.
Split into simpler sentences: Gluck was born into a wealthy Jewish family in London. Gluck's father was Joseph Gluckstein, whose brothers Isidore and Montague had founded J. Lyons and Co., a British coffee house and catering empire.