Understanding 「なんで... もんかね」


> 「二人とも、またこんなところで練習をしていたのかい？」
>
> 「仕方ないだろ。エレンの奴、一向に成功しねえんだから。カレンの方は優秀だってのに、なんで姉妹でここまで差が出る **もんかね** 」

What would be the usage or nuance of the bold もんかね? How is it different from
just のか? I know ものか can mean “definitely not” or “impossible”, but this
example seems to have a different nuance.




This もの/もん is the same as もの/もん you have asked before:

  * [What would be the function of the というものだ in this context?](https://japanese.stackexchange.com/q/82293/5010)

The difference is that the question marker か is used instead of だ. In this
case, the added nuance is "is that the way sisters work (in general)?", etc.
The speaker is talking not only about "these sisters" but also about "sisters
in general".

> なんで姉妹でここまで差が出るもんかね  
>  I wonder why (in general) there's this much difference between two sisters.

By the way, I think ものか/もんか meaning "I will never ～" is in the same vein. It
implies it's not a "one-time no" but "always impossible in any similar
situation".




This もの/もん is the same as もの/もん you have asked before:

  * [What would be the function of the というものだ in this context?](https://japanese.stackexchange.com/q/82293/5010)

The difference is that the question marker か is used instead of だ. In this
case, the added nuance is "is that the way sisters work (in general)?", etc.
The speaker is talking not only about "these sisters" but also about "sisters
in general".

> なんで姉妹でここまで差が出るもんかね  
>  I wonder why (in general) there's this much difference between two sisters.

By the way, I think ものか/もんか meaning "I will never ～" is in the same vein. It
implies it's not a "one-time no" but "always impossible in any similar
situation".

