In Advent Children, why Kadaj and his gang called Cloud as their "brother" ?

Kadaj and his gang have parts of JENOVA in their DNA (which is why they refere to her as "mother"). By calling cloud "brother" they hint at Cloud also carring parts of JENOVA, which is true in a way, as he also has geostigma, which is a sign of being spoiled with JENOVA-cells.