There are various different ways in which one might understand Alfonsina Storni's "Peso ancestral." First, there is the literal meaning from which to work:

You told me that my father and grandfather never cried, for they were strong men. As you said this, a tear fell into my mouth. It was venomous. Poor woman, who understands the pain I tasted in the tear, my soul cannot bear all of your burden.

This summary makes no attempt to be poetic, but it captures the events and expressed thoughts in the poem. Here is a possible interpretation:

My mother told me that the men in my family never cry. This was when I was a baby (perhaps crying myself). As she said this, a tear fell from her eye into my mouth. I was astonished by its bitterness. I could not bear the burden of grief that I tasted in my mother's tear.

This interpretation involves making some choices. You have to assume that the speaker is male and that the mother is rebuking him for crying, essentially by telling him that "boys don't cry." She attributes this to their strength, but when he tastes the intense bitterness of her tear, he realizes that she has had to be stronger than a man, bearing heavier burdens.

The reference to a cup (although there is, in fact, no cup) recalls Mark's Gospel 10.38, in which Jesus asks James and John, "Can ye drink of the cup that I drink of?" This is the cup of bitter sacrifice. In this case, the tears of sacrifice that come from a woman are too bitter for a man or a boy to taste.

I am working from the translation of this poem into English by Liz Henry.

The title of this poem, translated into English, is "ancestral burden," or literally ancestral weight. In the poem, the speaker is being addressed by another person—it is not clear who this person is. It could be another woman (the "frail woman" later in the poem might be self-addressed, or it might address the second person in the poem). It might be the speaker's mother, but this is conjecture.

The second person tells the speaker that the men of their culture do not cry. The speaker's father did not cry, and nor did her grandfather. Ironically, however, hearing this brings a tear to the speaker's eye and, when she tastes it, it is like "venom" in her mouth.

The idea of the poem is that, by forcing their men never to cry, the culture believes that it is strong and masculine—but in fact, all that is happening is that the women of the culture are forced to bear all the pain men repress. The men still feel pain and suffering, but they offload it onto their women—the "pain of centuries" falls upon the shoulders of women. This is a poem about women's emotional labor as a result of toxic masculinity. The speaker states that she cannot "bear / all your burden," but there appears to be no other option presented to her. This is how things have always been.

The poem "Peso Ancestral" illustrates how Argentinian men carry the burdens passed on from one generation to the next by suppressing their negative emotions and never crying. When the narrator finally tastes her tears, she gets a glimpse into the pain that men in society experience on a daily basis and cannot bear their burden.

In the first stanza, the speaker mentions that her grandfather and father never cried. She also compares the men in her family to steel. In the second stanza, the speaker describes how she began to cry when she was told about the burdens the men in her family suffer from every day. When she cries, tears flow down her face and into her mouth. The speaker compares the tears to poison as she swallows them. In the third stanza, the speaker laments to the poor women who understand the generational burdens and centuries of pain that she tastes by swallowing her tears.

Essentially, Alfonsina Storni is commenting on the cultural differences between Argentinian men and women. In Argentina, emotional and psychological burdens are passed down from generation to generation and repressed by the males in each family. Men are perceived as being strong and reserved in their society and never weep. The suppression painful emotions from one generation to the next increases exponentially over time, and the men are forced to carry their family's burdens. When the speaker cries, she says that she cannot bear the pain, which reveals that women in Argentina seldom experience this burden that society places on men.