No I don't think they were Jewish, but I don't really know, have only just spotted them. The three younger brothers were in an Orphanage in 1901. I spotted Leonard MARKESKY has some WW1 documentation - I'll go and have a look to see if there is enough available to record his religion. I just wondered if it was as easier surname for people to pronounce, or maybe there was anti-German feelings in 1911 and any foreign second name would be suspicious. What ever the reason it's been an uphill struggle to research. Very sad family, losing both parents, options for a young orphaned teenager rather limited, 'marriage' and children seemed a good way out I suppose. Well that's my take on it!
Julie