While Seabourn Sojourn does not have dedicated kids clubs, the ship does accommodate families with children. You'll typically see more children on the ship in the summer or holidays, during shorter sailings in the Mediterranean or Caribbean (when CEOs who are still working take their families on vacation, we were told). The minimum age is six months for sailings with ports; one year for ocean-crossing sailings.
When children are onboard, the line arranges for childcare -- =the Card Room is turned into an activity room, and low-key events are planned for the younger set. Keep in mind that on a ship this size, a sailing with 30 children is considered "a lot"; kids who splash in pools or take over hot tubs will not be looked upon favorably by other passengers.
Although there are no family cabins per se, different cabins can be combined into larger suites that are more suitable for people traveling together. No cabins offer third berths.