During a panel debate at the Pensions and Lifetime Savings Association's investment conference in Edinburgh, she said: "My suspicion is that many people are signed up because they feel they should, but that is subtly different to having bought into it, or understanding and believing that this is absolutely integral to sustainable long-term successful business.
"We need to think about cognitive diversity and how that impacts innovation and creativity and our ability to think about and anticipate the world in which we will continue to operate."
She said that being more honest about the debate would "remove one of the big barriers, the fear that is stifling the debate. Fear is a big barrier: fear of talking about this agenda and fear of saying the wrong thing."
Ms Gupta said that without good leadership firms' are unlikely to make much progress when it comes to improving internal cultures.
"You can't codify culture. Checklists and tick-boxes don't work. This is about governance, leadership and the way you manage risk.
"We haven't even started to scratch the surface of how you measure inclusivity openness in a culture and if you were able to do that, diversity may well follow. Maybe we are chasing this the wrong way around."
Ms Gupta said the fact 85 per cent of trustee board members are male is a matter of concern.
She said that positive discrimination, or at least positive action, would enable the balance to be tilted towards equality.
Banking Standards Board chief executive Alison Cottrell said the fact that you can't measure culture doesn't mean that you cannot judge it, or assess it and in particular it doesn't mean you can't manage it.
She said the approach the BSB has taken in its work with banks is that there is no such thing as a single measure of culture or a single good culture that everyone has to aspire to.
Ms Cottrell said: "A good culture is one that brings good outcomes for customers, or for the pride and professionalism of employees and for the broader economy and society.
"A firm and its board of directors need to continually challenge their own assumptions by going out and asking questions about how their organisation is perceived."
She said the BSB has boiled culture down to nine characteristics including honesty, reliability, competence, which the BSB has defined as the basis of trustworthiness.
Others are resilience, respect responsiveness openness, accountability and shared purpose.
In terms of short-term advice they would offer industry players, Michael Watkins, head of proposition development at Smart Pension, said: "Take 10 minutes to talk to a person who you would not normally speak to who is not involved with your organisation."
Overall Mr Watkins said the pensions industry is going to have to become less "protectionist", more open, and is going to have to give as much time and energy to the next generation of management.
He said: "You have to make time for things that you feel passionate about."
Ms Gupta's advice was: "Don't walk on by when you see these little things that are corrosive in a culture, which you might normally think you don't have enough time to address. Have a conversation about whether that is OK."
She said a lot of middle managers in the pensions sector at "a little scared to have the conversation, a bit scared to mark themselves out as troublemakers if the call out certain types of behaviour. They are only small things but they signal a huge amount."
Ian Fraser is a freelance journalist