Sending a SIGTERM or SIGINT to a ksh child kills entire process group in RHEL4

Issue

A ksh script spawns two background ksh scripts in RHEL4. The parent script exits and the children are left to run alone. When a sigterm is sent to one, the other dies as well.

Script parent:

#!/bin/ksh

./child1 &
./child2 &

Script child1:

#!/bin/ksh

while true
do
echo I am child1
sleep 30
done

Script child2:

#!/bin/ksh

while true
do
echo I am child2
sleep 90
done

Run parent, which will execute child1 and child2 as background processes. Their parent process id is listed at 1 because parent died and init took ownership.

When a sigterm is sent to child1, child2 dies as well.