It's always said that every painting has a story behind it, more like what it's saying so it's rather not exaggerative when you hear that voices are coming from a painting, what we should literally be asking is if those voices were heard literally or was felt through the sketching if such art work, and it's only the artist that can vividly illustrate what ever story about his or her painting, having said that I hope we can now clearly proceed with a clearer understanding.

An inheritance is likely something you receive legally and it automatically belongs to you, so if an old painting is being written down in grandma's will to be given to her children or grandchildren, it then means that literally there's more to that painting than what meets the eye, to any random person it might just be a painting but to the family it might hold memories or have high value in the market, so again getting rid of the painting is not in the options.
So back to the first question of whether I would investigate or stay away? Staying away is practically not in the options now so I would go for the first one which is to investigate the mystery behind the painting so as to demystify it, and curiosity would be one of my pushing factor to want to investigate, because for sure grandma wouldn't give me something that would hurt me or take my life, so I would be curious to unravel what ever it maybe that's the story behind that painting, how it came about and what bore forth that story.
As to what kind of secret might be hidden in it, I guess we can only but keep guessing until the mystery is demystify, and until then we are all left on suspense as to what those voices were echoing and how we can help.
Thank you all for your time, I hope the Adeyemi's family didn't keep you bored all through, see you next time 😘.
All images used here belongs to me.