Dmeck, Lumi is the biological daughter of Lalli and Inka, who is also a noita, so yes. She does take after them, and Ensi. Also I notice I confused my own timeline a bit, Lumi must be a teenager by now for Reynir to be living with Onni (she was already studying when that happened). So I guess they have younger children too, who require constant shepherding while swimming.
And I agree, Emil (probably?) doesn’t really have mage skill, but he’s very very keenly attuned with fire.