For Dunham & her sister to not think it was wrong does suggest lesser impropriety, but it doesn't eliminate it.
(I'm referring to multiple acts, not just the pebbles incident.)
Nor do the the Duggar family's greater offenses excuse her behavior.
I'm not saying what she did was somehow made OK by the Duggars. Merely that there's significant difference between the two, and that the circumstances with the Dunham one are
far, fa far more benign(or at least given what we know of both circumstances between the two). Something could come out that makes Dunham's example just as terrible as the Duggar one, but let's compare them directly;
Duggars;
Josh was
14 to 15 years old. That is plenty old enough to know you should not f*cking do that. He did it
while they were asleep, to hide. 4 of them(out of
5, FIVE of them)were also
his sisters, meaning he abused their trust in him as their big-brother. One of them(his sister's) was too young to even
know it was wrong, a further abuse of his position. His mother & father then took steps to cover it up as thoroughly as possible, including somehow convincing his sisters to "forgive" him, because his mother and father are quite clearly worse monsters than Josh could ever
think of being. All three of them should be in prison and their children taken from them, period.
Dunham;
Lena was 7(or perhaps a bit younger) and her contact was with her sister. No efforts were made to obfuscate this. We also have nothing that suggest it continued into an age where such actions by Lena would be considered grossly inappropriate or otherwise significantly troubling.