This week’s sedra is an object lesson in altruistic sibling devotion.

According to Rabbi Samson Raphael Hirsch (d.1888), Joseph decided to finally reveal his true identity to his brothers for very specific reasons.

Joseph had planted his goblet inside Benjamin’s sack when the brothers departed from Egypt.

Upon the ‘discovery’ that Benjamin had ‘stolen’ the goblet, Joseph demanded that Benjamin pay the price by remaining a slave in Egypt, while the others would be free to return home.

Unaware that Joseph had set-up the situation as a final test of the brothers’ dedication to the remaining child of Rachel, Judah pleaded with Joseph to have mercy on Benjamin.

Yet, crucially, he did not simply plead for mercy. Instead, he offered himself as a slave in place of his younger brother.

With this completely altruistic act, he finally demonstrated beyond any shadow of doubt that the fraternal animosity that had led to the sale of Joseph to Egypt in the first place was indeed removed from the brothers’ hearts.

Judah effectively offered his own freedom in place of that of his brother. When Joseph saw this, he realised that the circle was now complete.

The brothers had corrected the character flaws that had led to their tragic breakdown in sibling relationships.

A study on sibling relationships conducted in 2014 by a university in Utah, USA, followed 308 pairs of teenage siblings for three years.

It found that having a good relationship with a sibling increased levels of adolescents’ altruistic behaviour in general.

It is true that developing positive and healthy relationships between siblings can sometimes seem like an elusive goal for many parents.

But as this week’s sedra demonstrates, the rewards can be immeasurable.

And at the very least, it may just lead to a little more altruistic behaviour in years to come.

Yoni Birnbaum is rabbi of Hadley Wood Jewish Community