Are you suggesting there are zero behavioural differences between boys and girls?
To avoid gender, consider an example which uses race instead.
>It would help humanity to also give enough focus on black child development so that we could save their future, avoid the crimes they commit and their languishing in jails.
I've only switched one word, and while some may say it is not offensive, I could clearly foresee some people finding the underlying tone as offensive.
For an example of a difference which is sexist, imagine someone saying women are less fit for critical roles because they are more emotional, when in fact it is that our society works to repress male expression of emotions and both men and women are, at the core, emotional entities.